odbc连接scan ip_weblogic连接scan ip_weblogic数据源连接池(16)

将任务持久化到数据中。因为集群中节点依赖于来传播Scheduler实例的状态，你只能在使用 JDBC JobStore 时应用 Quartz 集群。

org.quartz.jobStore.isClustered 属性为 true，通知Scheduler实例要它参与到一个集群当中。weblogic连接scan ip

org.quartz.jobStore.clusterCheckinInterval

属性定义了Scheduler 实例检入到中的频率(单位：毫秒)。

Scheduler 检查是否其他的实例到了它们应当检入的时候未检入；

这能指出一个失败的 Scheduler 实例，且当前 Scheduler 会以此来接管任何执行失败并可恢复的 Job。

通过检入操作，Scheduler 也会更新自身的状态记录。clusterChedkinInterval 越小，Scheduler 节点检查失败的 Scheduler 实例就越频繁。默认值是 15000 (即15 秒)

集群实现分析

Quartz原来码分析:

基于表锁实现多Quartz_Node 对Job,Trigger,Calendar等同步机制

-- 锁定表
CREATE TABLE `QRTZ_LOCKS` (
  `LOCK_NAME` varchar(40) NOT NULL,
  PRIMARY KEY (`LOCK_NAME`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- 记录
+-----------------+
| LOCK_NAME       |
+-----------------+
| CALENDAR_ACCESS | 
| JOB_ACCESS      | 
| MISFIRE_ACCESS  | 
| STATE_ACCESS    | 
| TRIGGER_ACCESS  | 
+-----------------+

通过行级别锁实现多节点处理

/**
 * Internal database based lock handler for providing thread/resource locking 
 * in order to protect resources from being altered by multiple threads at the 
 * same time.
 * 
 * @author jhouse
 */
public class StdRowLockSemaphore extends DBSemaphore {

    /*
     * Constants.
     * 锁定SQL语句
     * 
     */
    public static final String SELECT_FOR_LOCK = "SELECT * FROM "
            + TABLE_PREFIX_SUBST + TABLE_LOCKS + " WHERE " + COL_LOCK_NAME
            + " = ? FOR UPDATE";

    /**
     * This constructor is for using the <code>StdRowLockSemaphore</code> as
     * a bean.
     */
    public StdRowLockSemaphore() {
        super(DEFAULT_TABLE_PREFIX, null, SELECT_FOR_LOCK);
    }

    public StdRowLockSemaphore(String tablePrefix, String seletWithLockSQL) {
        super(tablePrefix, selectWithLockSQL, SELECT_FOR_LOCK);
    }

    /**
     * Execute the SQL select for update that will lock the proper database row.
	 * 指定锁定SQL
     */
    protected void executeSQL(Connection conn, String lockName, String expandedSQL) throws LockException {
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = conn.prepareStatement(expandedSQL);
            ps.setString(1, lockName);

            if (getLog().isDebugEnabled()) {
                getLog().debug(
                    "Lock '" + lockName + "' is being obtained: " + 
                    Thread.currentThread().getName());
            }
            rs = ps.executeQuery();
            if (!rs.next()) {
                throw new SQLException(Util.rtp(
                    "No row exists in table " + TABLE_PREFIX_SUBST + 
                    TABLE_LOCKS + " for lock named: " + lockName, getTablePrefix()));
            }
        } catch (SQLException sqle) {
            if (getLog().isDebugEnabled()) {
                getLog().debug(
                    "Lock '" + lockName + "' was not obtained by: " + 
                    Thread.currentThread().getName());
            }
            throw new LockException("Failure obtaining db row lock: "
                    + sqle.getMessage(), sqle);
        } finally {
            if (rs != null) { 
                try {
                    rs.close();
                } catch (Exception ignore) {
                }
            }
            if (ps != null) {
                try {
                    ps.close();
                } catch (Exception ignore) {
                }
            }
        }
    }

    protected String getSelectWithLockSQL() {
        return getSQL();
    }

    public void setSelectWithLockSQL(String selectWithLockSQL) {
        setSQL(selectWithLockSQL);
    }
}

   /**
     * Grants a lock on the identified resource to the calling thread (blocking
     * until it is available).
     * 获取QRTZ_LOCKS行级锁
     * @return true if the lock was obtained.
     */
    public boolean obtainLock(Connection conn, String lockName) throws LockException {
        lockName = lockName.intern();

        Logger log = getLog();

        if(log.isDebugEnabled()) {
            log.debug(
                "Lock '" + lockName + "' is desired by: "
                        + Thread.currentThread().getName());
        }
        if (!isLockOwner(conn, lockName)) {
            executeSQL(conn, lockName, expandedSQL);
            
            if(log.isDebugEnabled()) {
                log.debug(
                    "Lock '" + lockName + "' given to: "
                            + Thread.currentThread().getName());
            }
            getThreadLocks().add(lockName);
            //getThreadLocksObtainer().put(lockName, new
            // Exception("Obtainer..."));
        } else if(log.isDebugEnabled()) {
            log.debug(
                "Lock '" + lockName + "' Is already owned by: "
                        + Thread.currentThread().getName());
        }
        return true;
    }

    /**
     * Release the lock on the identified resource if it is held by the calling thread.
     * 释放QRTZ_LOCKS行级锁
     */
    public void releaseLock(Connection conn, String lockName) {
        lockName = lockName.intern();

        if (isLockOwner(conn, lockName)) {
            if(getLog().isDebugEnabled()) {
                getLog().debug(
                    "Lock '" + lockName + "' returned by: "
                            + Thread.currentThread().getName());
            }
            getThreadLocks().remove(lockName);
            //getThreadLocksObtainer().remove(lockName);
        } else if (getLog().isDebugEnabled()) {
            getLog().warn(
                "Lock '" + lockName + "' attempt to return by: "
                        + Thread.currentThread().getName()
                        + " -- but not owner!",
                new Exception("stack-trace of wrongful returner"));
        }
    }

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